Road milling, mining, and trenching equipment utilizes bits and/or picks traditionally set in a bit assembly. Bit assemblies can include a bit and/or pick retained within a bore in a base bock. Bit assemblies can also include a bit and/or pick retained by a bit holder and the bit holder retained within a bore in a base block. A plurality of the bit assemblies are mounted on the outside of a rotatable drum, typically in a V-shaped or spiral configuration. A plurality of the bit assemblies can also be mounted on an endless chain and plate configurations. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits and/or picks, bit holders, and base blocks may wear down or break over time due to the harsh road degrading environment. Additionally, the forces and vibrations exerted on the bit assemblies may cause the bit and/or pick to wear away the bore in the base block, the bit and/or pick to wear away the bore in the bit holder, or the bit holder to wear away the bore in the base block. As a result, the diameter of the bore of the base block, or the diameter of the bore in the bit holder, increases over time, decreasing the interference contact between the bit and/or pick and the bore of the base block, the bit and/or pick and the bore of the bit holder, or the bit holder and the bore of the base block, thereby damaging the bit holder or base block and requiring replacement of the bit holder or base block long before the standard minimum lifetime required by the industry.
To prolong the life of the bit assembly, and the bit holder and/or the base block, a bit and/or pick comprising a diametrically expanding retainer circumferentially disposed around a shank of the bit and/or pick is provided to maintain the interference contact between the bore of the base block or the bore of the bit holder as the diameter of the bore of the base block or the diameter of the bore of the bit holder block, respectively, increases from use. The bit and/or pick also includes a washer around the shank of the bit and/or pick adapted to engage a forward outer surface of the retainer to achieve alignment between the shank of the bit and/or pick and the bore of the bit holder or base block. All components associated with the bit are replaced with each bit exchange. The bit holder or base block remains unchanged. The service life of the bore and base of the bit holder or base block are substantially increased due to the non-rotating washer, due to the bore wear compensation, and due to the coaxial alignment of the shank of the bit.